Warewashers may be used for cleaning and sanitizing pots, pans, plates, glasses, eating utensils, and other wares. The term warewasher is used synonymously with the term dishwasher herein. Typically, the incoming water to a warewasher is supplied at a temperature of 140° F., the standard temperature achieved by conventional hot water heaters. However, in other cases the incoming water temperature may be as low as 110° F. Warewashers typically have a water booster heater to raise the water temperature to a desired temperature, typically around 180° F. Batch-type warewashers are units that clean wares on a batch basis, that is, one load at a time. Between cleaning operations, clean wares from one load are removed from a wash chamber and dirty wares of the next load are placed into the wash chamber.
Currently, warewashers are provided with two fixed temperature rise options, either a 40° F. rise or a 70° F. rise. The desired temperature rise option is programmed at the factory or by a service technician based upon an anticipated incoming water temperature and results in a wash cycle of a set duration, where the set duration for 40° F. rise is shorter than the set duration for 70° F. rise. In most commercial applications it is desirable to maximize the number of wash loads or batches that a warewasher can handle in any given time period, with the entire cleaning cycle often being completed in a matter of a few minutes as compared to thirty minutes or more for typical non-commercial dishwashers. Accordingly, it would be desirable to provide a new system and a method of controlling the duration of the wash cycle in attempt to achieve such a goal.
During various cycles of warewasher operation it is often necessary to detect the level of water within the wash chamber. Electrical probes have been used in the past for such purposes. However, over time lime deposits can form on such probes reducing the probe's ability to accurately detect the presence/absence of liquid in the wash chamber. One attempt to address the lime deposit problem is described in U.S. Pat. No. 6,223,129 where a linear regression technique is used. However, the system of U.S. Pat. No. 6,223,129 does not track the build up of lime deposits over time and does not provide the ability to detect the presence of a metal utensil shorting the electrodes of the probe. Accordingly, an improved water level detection system and method is desirable.
Chemicals such as detergents, sanitizers and rinse agents are often used in connection with warewasher systems. Such chemicals are typically fed into the wash chamber under control of respective pumps. When the supply of one of these chemicals runs out, the absence of the chemical from the wash and/or rinse operations can detrimentally affect cleaning and/or sanitation. Accordingly, chemical sensors have been used in the past along chemical feed lines leading from the chemical supply to the wash chamber. Exemplary of such a chemical sensor system is that described in U.S. Pat. No. 5,378,993. Warewashers have also been provided with a chemical out indicator (e.g., an LED, LCD or other light display) to advise a user if the chemical is not present in the line to prompt the user to check the line and or add more chemicals. After the new chemicals have been added, users have also been provided the ability to prime the chemical feed line by manually depressing a chemical prime button. However, users do not always prime the feed line properly. Accordingly, it would be desirable to provide an improved chemical feed line sensor system and method and associated arrangement to prime a chemical feed line.